文档介绍：外文原文:
The Development of World Electric otive
Electric otive itself with the original motive accept catenary sent by the current as a source of energy, from otive traction motor drive the wheels. With electric otive power, thermal efficiency, fast, strong and reliable operation Guozainaili major advantages, but do not pollute the environment, and particularly applicable to the busy railway transportation and tunnels, the slope of the mountain railway.
Electric otive from the contact line access to electricity, catenary power supply current otives are both DC and AC. The current system different, not with the electric otive, can be divided into basically straight-DC electric otive, the TAC-DC electric otive, the TAC-Direct-AC electric otive three.
Straight-DC electric otive using DC power supply system, traction substation equipped with rectifier devices, it will e a three-phase AC DC, and then to access the . Therefore, the electric otive can be made online directly from the contact supply DC Series traction motor use, which simplifies the otive equipment. DC system's weaknesses are catenary low voltage, typically l500V or 3000 V, the contact wire request is rough, it is necessary to consume a large amount of non-ferrous metals, and increased construction investment.
TAC - DC electric otive powered by AC system, most of the world's countries use the frequency (50Hz)